Exemplary embodiments pertain to the art of gas turbine engines and, more particularly, to a preloaded ball bearing assembly for use in gas turbine engines.
Ball bearings are commonly used in gas turbine engines. They position the rotation parts of the engine relative to the static parts and transfer radial and axial loads from the rotor to the static structure. In a preloaded ball bearing arrangement, two ball bearings are positioned in close proximity. They are loaded against each other, with a load either pushing the outer rings apart or pulling them together.
Multiple benefits are achieved with preloaded ball bearings. They reduce radial and axial displacement of a rotor, when compared to a single ball bearing. Additionally, they increase moment stiffness in comparison to a single ball bearing. However, preloaded ball bearings may suffer from premature failure if thermal growth and associated displacement increase the axial preload above the capability of one or both of the bearings.
Prior arrangements of preloaded ball bearings have used a configuration with a preload spring combined with an outer ring which can float in a radial clearance. The drawback of this approach is that thermal growth can cause the gap between the bearing and housing to close, resulting in a preload which overloads the bearing and causes premature failure.